In Long Term Evolution (LTE), to meet the demands of users for a higher radio bearer peak rate, two types of radio bearers (RB) are provided: one is referred to as a master cell group (MCG) bearer and the other is referred to as a split bearer. The Split bearer has a higher peak rate than that of the MCG bearer. FIG. 1 is a schematic diagram of a protocol stack architecture of an MCG bearer and a Split bearer. As shown in FIG. 1:
In user equipment (UE), one MCG bearer is associated with one Packet Data Convergence Protocol (PDCP) entity and one Radio Link Control (RLC) entity. In FIG. 1, the PDCP entity and the RLC entity are respectively represented by PDCP1 and m-RLC1, the m-RLC1 entity is associated with one corresponding Media Access Control (MAC) entity m-MAC, and the m-MAC entity corresponds to a first base station (MeNB). The protocol entities in the user equipment have their respective peer protocol entities on a network side, where peer protocol entities of the PDCP1 entity, the m-RLC1 entity, and the m-MAC entity are respectively a peer p-PDCP1 entity, a peer pm-RLC1 entity, and a peer pm-MAC entity in the MeNB. All downlink data packets of the MCG bearer are from the peer p-PDCP1 entity to the peer pm-RLC1 entity and then to the peer pm-MAC entity, and are then sent by the peer pm-MAC entity to the m-MAC entity through an air interface. Then, the m-MAC entity finally delivers the received data packets to the PDCP1 entity through the m-RLC1 entity. A transmission path of uplink data packets of the MCG bearer is opposite to a transmission path of downlink data packets of the MCG bearer.
In the user equipment, one Split bearer is associated with one PDCP2 entity and two RLC entities. In FIG. 1, the two RLC entities are respectively represented by m-RLC2 and s-RLC, where the m-RLC2 entity is associated with the m-MAC entity, the s-RLC entity is associated with an s-MAC entity, the m-MAC entity corresponds to the first base station MeNB, and the s-MAC entity corresponds to a second base station (SeNB). The protocol entities in the user equipment have their respective peer protocol entities on the network side, where peer protocol entities of the PDCP2 entity, the m-RLC2 entity, and the m-MAC entity are respectively a peer p-PDCP2, a peer pm-RLC2, and a peer pm-MAC in the MeNB; and peer protocol entities of the s-RLC entity and the s-MAC entity are respectively a peer ps-RLC entity and a peer ps-MAC entity in the SeNB. Some of downlink data packets of the Split bearer are from the peer p-PDCP2 entity to the peer pm-RLC2 entity and then to the peer pm-MAC entity, and are then sent by the peer pm-MAC entity to the m-MAC entity through an air interface. Then, the m-MAC entity finally delivers these received data packets to the PDCP2 entity through the m-RLC2 entity. The other downlink data packets of the Split bearer are sent by the peer p-PDCP2 entity to the peer ps-RLC entity through an interface between the MeNB and the SeNB, the peer ps-RLC entity delivers these data packets to the peer ps-MAC entity; then, the peer ps-MAC entity sends these data packets to the s-MAC entity through an air interface. Then the s-MAC entity finally delivers these received data packets to the PDCP2 entity through the s-RLC entity. A transmission path of uplink data packets of the Split bearer is opposite to a transmission path of downlink data packets of the Split bearer.
The MCG bearer and the Split bearer can be transformed into each other according to factors such as a change in channel environment and a data transmission requirement. However, in the prior art, when a Split bearer needs to be transformed into an MCG bearer, an MeNB determines, according to a measurement report about an SeNB that is sent by a user equipment, whether to transform a Split bearer of the user equipment into an MCG bearer, and if yes, separately notifies the user equipment and the SeNB. The user equipment needs to release an s-MAC entity and an s-RLC entity of the Split bearer, and the SeNB needs to release a peer ps-MAC entity and a peer ps-RLC entity of the Split bearer. Subsequently, when the MCG bearer obtained after the transformation needs to be transformed back to an Split bearer, the MeNB determines, according to another measurement report about the SeNB that is sent by the user equipment, whether to transform the MCG bearer back to a Split bearer, and if yes, separately notifies the user equipment and the SeNB; and the user equipment needs to re-establish the s-MAC entity and the s-RLC entity for the bearer, and the SeNB also needs to re-establish the peer ps-MAC entity and the peer ps-RLC entity for the bearer.
In the foregoing conventional manner, there is a relatively large amount of air interface signaling interaction between the user equipment and the MeNB, and there is also a relatively large amount of backbone network signaling interaction between the MeNB and the SeNB, which increases signaling load of the network and introduces a relatively long signaling delay. In addition, releasing and re-establishing a protocol entity related to a bearer results in relatively low resource utilization.